The present invention relates to an arrangement for optimizing the running clearance for turbomachines that are at least partially of the axial type, by controlling or regulating the inner diameter, which is relevant to the running clearance, of at least one stator structure that surrounds a rotor blade ring.
Persons skilled in the art usually refer to this technology as Active Clearance Control, or ACC. As a rule, the known designs using this construction are based on the principle of supplying areas of the housing or stator elements with a flow of low-temperature air, i.e. cooling air, in a defined fashion in order to influence the running clearance via thermal contraction of these components. A reduction or interruption in the flow of cooling air causes the components to expand again. This procedure is more effective the greater the temperature difference between the component and the cooling air. Preferably, a hot turbine stator is supplied with relatively cool air from a compressor. Such an arrangement is disclosed for example in U.S. Pat. No. 6,454,529 B1. In compressors, the development also includes active monitoring of the maintaining of the clearance. Thermal influencing of the housing or stator reaches its limit in particular in compressors, due to small temperature differences. Thus, there is a demand for systems that perform better and that react faster.